Cooling arrangement for brush seal

ABSTRACT

A brush seal adapted to restrict a fluid flow through a gap between a first component and a second component, comprising: a body; a brush pack secured to the body; and a passage through the body for introducing a cooling flow to said gap. The passage has a first end that is exposed to the gap and a second end that is not exposed to the gap. The passage discharges a cooling flow to the brush seal, the cooling flow being discrete from the fluid flow.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional application of U.S. patent applicationSer. No. 10/064,681, filed Aug. 6, 2002, entitled COOLING ARRANGEMENTFOR BRUSH SEAL, By Mark E. Addis.

BACKGROUND OF THE INVENTION

This invention relates to brush seals. Specifically, this inventionrelates to cooling arrangements for brush seals.

New gas turbine engine designs typically increase efficiency byoperating at higher temperatures. These higher operating temperaturesaffect, among other components, the brush seals used in these designs.As the operating temperatures increase, these higher operatingtemperatures may approach, or even surpass, the recommended temperaturelimits for the materials comprising the brush seal.

A related concern in brush seal design is the temperature of bristletips. As the land surface of the runner rotates against the brush sealbristles, the friction therebetween creates heat. Excessive temperaturesat the bristle tips caused by this friction can deteriorate the bristletips and the land surface. Excessive bristle tip temperatures can alsocause duck-footing or smearing of the bristles. Finally, excessivebristle tip temperatures can cause the bristles to fuse to the runner.These conditions can rapidly decrease the performance of the brush seal.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved brushseal.

It is a further object of the present invention to provide a brush sealthat can operate at increased operating temperatures.

It is a further object of the present invention to provide a brush sealthat limits bristle tip temperatures.

It is a further object of the present invention to provide a brush sealwith a cooling arrangement.

These and other objects of the present invention are achieved in oneaspect by a brush seal. The brush seal is adapted to restrict a fluidflow through a gap between a first component and a second component, andcomprises: a body; a brush pack secured to said body; and a passagethrough said body for introducing a cooling flow to said gap. Thepassage has a first end that is exposed to said gap and a second endthat is not exposed to said gap.

These and other objects of the present invention are achieved in anotheraspect by an apparatus, comprising: a first component; a secondcomponent; a brush seal mounted on said first component and contactingsaid second component, wherein said brush seal inhibits a fluid flowfrom passing between said first component and said second component; andan opening for discharging a cooling flow to said brush seal, saidcooling flow discrete from said fluid flow.

These and other objects of the present invention are achieved in anotheraspect by a method of cooling a brush seal. The method comprises thesteps of: providing a brush seal, first component and second component;placing said brush seal between said first component and said secondcomponent to inhibit a fluid flow from passing therebetween; andsupplying a cooling flow to said brush seal.

BRIEF DESCRIPTION OF DRAWINGS

Other uses and advantages of the present invention will become apparentto those skilled in the art upon reference to the specification and thedrawings, in which:

FIG. 1 is a cross-sectional view of a gas turbofan engine;

FIG. 2 is a partial cross-sectional view of one alternative embodimentof a brush seal cooling arrangement of the present invention;

FIG. 3 is a perspective view, in partial cross-sectional, of anotheralternative embodiment of a brush seal cooling arrangement of thepresent invention; and

FIG. 4 is a cross-sectional view of another alternative embodiment of abrush seal cooling arrangement of the present invention.

DETAILED DESCRIPTION

FIG. 1 displays a conventional gas turbofan engine 10. Starting at theupstream end, or inlet 11, the major components of the engine 10 includea fan section 13, a low pressure axial compressor 15, a high pressureaxial compressor 17, a burner section 19, a high pressure turbine 21, alow pressure turbine 23, and a nozzle 25. Generally speaking, the engine10 operates as follows. Air enters the engine 10 through the inlet 11,travels past the fan section 13 (which can be considered part of thecompressor), becomes compressed by the compressors 15, 17, mixes withfuel, and combusts in the burner section 19. The gases from the burnersection 19 drive the turbines 21, 23, then exit the engine 10 throughthe nozzle 25.

As designed, the engine 10 inducts more air than is necessary forcomplete combustion. This surplus allows for the use of a portion of theair to perform other functions. For example, the surplus air can driveaccessories (not shown) such as air conditioning units, hydraulic pumpsand thrust reverser actuators. In addition, removing surplus air canhelp avoid compressor surge. However, the main purpose of extracting airis for cooling the engine 10.

Cooling can occur by extracting surplus air from a cooler section of theengine 10 and delivering the extracted air to a hotter section of theengine 10. For example, the extraction could occur from the fan section13 or the compressor sections 15, 17 to supply cooling air to theturbine sections 21, 23.

The extraction of surplus air can occur in two ways. First, theextracted air can travel internally through the engine 10. Second, theextracted air can travel externally from the engine 10. FIG. 1 showsboth possibilities.

The internal cooling air path in FIG. 1 relies on a hollow shaft 27connecting the low pressure compressor 15 and low pressure turbine 23.Air bleeds from the low pressure compressor 15, enters the shaft 27through openings therein, exits the shaft 27 and arrives at the bladesof the low pressure turbine 23.

The external cooling air path of FIG. 1 relies on a duct 29 adjacent theengine 10. Air bleeds from the high pressure compressor 17, enters theduct 29, travels through the duct 29 and arrives at the vanes of thehigh pressure turbine 21. The present invention utilizes one or both ofthese cooling paths to cool a brush seal. The cooling arrangement of thepresent invention allows the engine 10 to operate at elevatedtemperatures. FIGS. 2 and 3 each display a possible brush sealarrangement.

FIG. 2 displays a brush seal 51 mounted to a first component 53 of theengine 10. The brush seal 51 could mount to first component 53 usingconventional techniques, for example with a removable flange (notshown). With the flange removed from the first component 53, the brushseal 51 could mount to a groove (not shown) in the first component 53.The flange is then fastened to the first component 53 to sandwich thebrush seal 51 therebetween. The first component 53 is typically astationary component of the engine 10, such as a diffuser case.

The brush seal 51 has a body, typically comprising a backing plate 55and a side plate 57. The side plate 57 could include a windage cover 59.Alternatively, the windage cover 59 could comprise a separate piece fromthe side plate 57.

A brush pack 61 resides between the backing plate 55 and the side plate57. A plurality of fine wire bristles comprise the brush pack 61. Thebrush pack 61 and the plates 55, 57 secure together using knowntechniques, such as by welding. Although the figures show the bristlesextending radially within the engine 10, brush seals are also used toclose gaps between upstream and downstream components. In thisarrangement, the bristles preferably extend axially (not shown) withinthe engine.

The brush pack 61 engages a second component 63 of the engine 10.Depending upon the application (e.g. dynamic or static), the secondcomponent 63 could be a rotating component of the engine 10 (a dynamicapplication) or another stationary component of the engine 10 (a staticapplication). Typically, the second component 63 is a rotatingcomponent, such as a turbine shaft.

Regardless of the brush seal 51 having a static or dynamic application,the purpose of the brush seal 51 is to restrict a fluid flow (e.g. air)through a gap 65 between the first component 53 and the second component63.

The friction created by the metallic brush pack 61 engaging the metallicrotating component 63 of the engine 10 produces localized heating indynamic applications. Excessive heat build-up in this area candeteriorate the bristle tips and the runner land surface. In addition, ahigh ambient temperature within the gap 65 between the first and secondcomponents 53, 63 can also deteriorate the brush pack 61 in both staticand dynamic applications. The present invention can help control heatbuild-up at the bristle tips and help lessen the effects of high ambienttemperature in the gap 65.

The body of the brush seal 51 can have a passageway 67 extendingtherethrough. The passageway can extend through any suitable part of thebody of the brush seal 51. For the single stage brush seal shown in FIG.2, the passageway 67 preferably extends through the side plate 57. Thepassageway 67 has an inlet at the front face of the side plate 57 and anoutlet at the rear face of the side plate 57 adjacent the brush pack 61.If the side plate 57 includes a windage cover 59 (such as seen in FIG.2), the passageway 67 could extend through the windage cover 59. Thepassageway 67 allows cooling air C to enter the gap 65 and to impingeupon the brush pack 61. The cooling air C helps reduce the heat build-upat the interface between the brush seal 51 and the second component 63or reduce the high ambient temperature within the gap 65.

Preferably, the cooling air C originates from another location withinthe engine. In other words, the cooling air C is discrete from the fluidflow within the gap 65 between the first and second components 53, 63 ofthe engine 10. The cooling air C preferably should also exhibit a lowertemperature than the fluid within the gap 65 to help reduce theaforementioned heat build-up.

The first component 53 helps the cooling air C arrive at the brush seal51. The first component 53 has a passageway 69 therethrough. Thepassageway 69 is located so as to communicate with the passageway 67 ofthe brush seal 51. The cooling air, bled from another section of theengine 10 (such as the compressor 13, 15, 17), travels through thepassageways 67, 69 and enters the gap 65. Using the arrangement shown inFIG. 1, the external duct 29 of the engine 10 could supply the coolingair C to the passageway 69. The external duct 29 bleeds air from thehigh pressure compressor 17. Other methods and sources of cooling air,however, could be used to supply the passageways 67, 69. Since the firstcomponent 53 surrounds the inlet of the passageway 67 and the passageway69 communicates with the passageway 67, the inlet of the passageway 67is not exposed to the gap 65 between the first and second components 53,63 of the engine 10.

The passageways 67, 69 could have any suitable size that provides asufficient amount of cooling air C to the brush seal 51. The passageways67, 69 could also have shapes different than those shown in FIG. 2 inorder to allow the cooling air C to impinge upon a desired location ofthe brush seal 51.

FIG. 3 displays a cooling arrangement for a multiple stage brush seal151. The brush seal 151 operates in the same manner as theaforementioned brush seal 51. In other words, the brush seal 151inhibits fluid flow through a gap 165 between a first component 153 anda second component 163.

Each stage of the brush seal 151 includes a backing plate 155, sideplate 157 and brush pack 161. The backing plate 155 of each upstreamstage serves as the windage cover 159 for the next downstream stage ofthe brush seal 151.

Each stage of the brush seal 151 also includes a passageway 167 tointroduce cooling air C to the brush packs 161. Although shown asextending radially through the side plates 157, the passageways 167could travel through any area of the brush seal body and could followany desired path through the brush seal body.

The passageways 167 communicate with passageways 169 in the firstcomponent 153. A common header 171 in the first component 153 couldsupply the cooling air C to the passageways 169. A supply passageway 173allows the cooling air C to enter the first component 153. Any othercooling air supply arrangement, however, could be used (such asindividual supplies for each passageway 167).

FIG. 4 provides another embodiment of a brush seal arrangement. Similarto the aforementioned brush seals, brush seal 251 mounts to a firstcomponent 253 of the engine. The brush seal 251 extends from the firstcomponent 253 to engage a second component 263 of the engine 10. Thebrush seal 251 serves to restrict a fluid flow (e.g. air) through a gap265 between the first component 253 and the second component 263.

Differently than the earlier embodiments, the second component 263supplies the cooling air C to the brush seal 251. If, as seen in FIG. 4,the second component 263 is a turbine shaft, the shaft comprises ahollow interior 275 with passageways 277 extending through an outer wall279 in a circumferential arrangement around the shaft.

The passageways 277 are located adjacent the interface between the brushseal 251 and the second component 263. Preferably, the passageways 277are located upstream of such interface as seen in FIG. 4. Otherarrangements, however, are possible (e.g. between stages of a multiplestage brush seal).

The passageways 277 could have any suitable size to provide a sufficientamount of the cooling air C to the interface between the brush seal 251and the second component 263. Although shown as linear and a constantdiameter, the passageways 277 could have any suitable shape or taperthat allows the cooling air C to impinge upon a desired location of thebrush seal 251.

Using the arrangement shown in FIG. 1, the cooling air C could bleedfrom another section of the engine 10 such as the compressor 13, 15, 17.The cooling air C would depart the compressor 13, 15, 17, travel throughthe turbine shaft, exit the passageways 277, and enter the gap 265between the first and second components 253, 263 of the engine 10. Othermethods and sources of cooling air, however, could be used to supply thepassageways 277.

The present invention has been described in connection with thepreferred embodiments of the various figures. It is to be understoodthat other similar embodiments may be used or modifications andadditions may be made to the described embodiment for performing thesame function of the present invention without deviating therefrom.Therefore, the present invention should not be limited to any singleembodiment, but rather construed in breadth and scope in accordance withthe recitation of the appended claims.

The invention claimed is:
 1. A system comprising: a brush seal having abody; a brush pack secured to said body; said body including a backingplate and a side plate having a portion spaced from said brush pack andforming a gap therewith; said side plate having a first face and asecond face and a first fluid passageway having an inlet in said firstface and an outlet in said second face for discharging a cooling fluidinto said gap between said brush pack and said side plate, wherein saidfirst and second faces each extend substantially parallel to alongitudinal axis of said brush pack; a first engine component having asurface which abuts said first face and a second fluid passagewayextending through said first engine component and forming a continuousfluid passageway with said first fluid passageway; said second fluidpassageway having an outlet in said surface of said first enginecomponent; said outlet of said second fluid passageway being in contactwith the inlet of said first fluid passageway to form said continuousfluid passageway and for delivering cooling fluid from said second fluidpassageway to said first cooling passageway; and said brush pack havinga first end which contact said body and a second end which contacts asurface of a second engine component.
 2. The system of claim 1, whereinone of said engine components is a rotating component.
 3. The system ofclaim 1, wherein said second fluid passageway extends solely within saidfirst engine component.
 4. The system of claim 1, wherein said secondfluid passageway introduces cooling air discrete from fluid flowingwithin a gap between said first engine component and said second enginecomponent.
 5. The system of claim 1, wherein said first fluid passagewayextends diagonally through said side plate.
 6. A system comprising: abrush seal having a body; a brush pack secured to said body; said bodyincluding a backing plate and a side plate having a portion spaced fromsaid brush pack and forming a gap therewith; said side plate having afirst face and a second face and a first fluid passageway having aninlet in said first face and an outlet in said second face fordischarging a cooling fluid into said gap between said brush pack andsaid side plate; a first engine component having a surface which abutssaid first face and a second fluid passageway extending through saidfirst engine component and forming a continuous fluid passageway withsaid first fluid passageway; said second fluid passageway having anoutlet in said surface of said first engine component; said outlet ofsaid second fluid passageway being in contact with the inlet of saidfirst fluid passageway to form said continuous fluid passageway and fordelivering cooling fluid from said second fluid passageway to said firstcooling passageway; said brush pack having a first end which contactsaid body and a second end which contacts a surface of a second enginecomponent; and wherein said side plate has an integral windage coverlocated beneath the outlet of said first fluid passageway.
 7. A systemcomprising: a brush seal having a body; a brush pack secured to saidbody; said body including a backing plate and a side plate having aportion spaced from said brush pack and forming a gap therewith; saidside plate having a first face and a second face and a first fluidpassageway having an inlet in said first face and an outlet in saidsecond face for discharging a cooling fluid into said gap between saidbrush pack and said side plate; a first engine component having asurface which abuts said first face and a second fluid passagewayextending through said first engine component and forming a continuousfluid passageway with said first fluid passageway; said second fluidpassageway having an outlet in said surface of said first enginecomponent; said outlet of said second fluid passageway being in contactwith the inlet of said first fluid passageway to form said continuousfluid passageway and for delivering cooling fluid from said second fluidpassageway to said first cooling passageway; said brush pack having afirst end which contact said body and a second end which contacts asurface of a second engine component; and a windage cover attached tosaid side plate, said windage cover being located below the outlet ofsaid first fluid passageway.